Cococubed.com Laminar Flame Speedup By Neon-22
Home Teaching materials Astronomy research ... White dwarf supernova ... Fallback ... Ti44 + Ni56 ... He shell flash ... SNIa ignition ... Flames with 22Ne ... P-rich NSE ... Verification Astronomy codes Astronomy talks Astronomy images Outreach Family album Bicycle adventures Artwork Contact us: J.D. Maldonado F.X.Timmes, my vitae	One unambiguously answered question about white dwarf supernovae is how the composition of the white dwarf affects the explosion. This paper shows that enrichment of the white dwarf with 22Ne, which is formed during fusion of helium in the progenitor main sequence star, speeds up the laminar flame in the early stages of the explosion. We tabulate the flame speedup for different initial 12C and 22Ne abundances and for a range of densities. This increase in the laminar flame speed - about 30% for a 22Ne mass fraction of 6% - affects the deflagration just after ignition near the center of the white dwarf, where the laminar speed of the flame dominates over the buoyant rise, and in regions of lower density ~107 g/cc where a transition to distributed burning is conjectured to occur. The increase in flame speed will decrease the density of any transition to distributed burning. This finding means that distant supernovae, which exploded long ago when the universe was systematically poorer in heavy elements, are somewhat different than nearby supernovae. It remains to be seen whether this translates into any systematic errors in using type Ia supernovae as "standard candles." Fig. 1 - Flame speeds computed with a 130-nuclide network, a 430-nuclide network, and those of Timmes and Woosley. Fig 2 - Abundances of selected isotopes for a hydrostatic burn at 2x109 g/cc and with an initial carbon mass fraction of 0.3. A more detailed table than what is found in the printed journal article may be found here on Ed Brown's web site. Some unpublished figures from the work describes above: Isotopes, 108 g/cc , X(C12)=0.3, X(Ne22)=0.0 Thermodynamics, 108 g/cc, X(C12)=0.3, X(Ne22)=0.0 Thermodynamics, 108 g/cc, X(C12)=0.5, X(Ne22)=0.0 Thermodynamics, 108 g/cc, X(C12)=0.5, X(Ne22)=0.06